Abstract. Black thyroid is an uncommon phenomenon of black pigmentation of thyroid parenchyma induced by chronic minocycline therapy. Thyroid tumors associated with black pigmented thyroid are rare. We describe here a 42-year-old woman with a black thyroid associated with hyalinizing trabecular tumor (HTT). The patient presented with a palpable left-sided thyroid nodule. She had taken minocycline for aphthous stomatitis and an oral ulcer for 9 years. The findings of fine needle aspiration biopsy and BRAF mutation analysis suggested a papillary carcinoma. The patient underwent a neartotal thyroidectomy with central compartment node dissection. The surgical specimen showed a diffuse black thyroid and a 2-cm non-pigmented, well-circumscribed nodule in the left thyroid. Histopathologically, numerous black pigmented follicular epithelial cells and colloid were seen throughout the thyroid parenchyma, and the nodule was composed of elongated, polygonal cells in trabecular arrangement and dense hyaline stromas. The tumor cells showed a strong positive cytoplasmic reaction to Ki 67. All of these findings suggested a HTT, or a hyalinizing trabecular variant of papillary carcinoma, arising in a black thyroid. To our knowledge, this is the first case of black thyroid associated with HTT. BLACK thyroid, or black pigmentation of the thyroid, was first described in humans in 1976 [1]; to date only 64 cases have been reported in the English language literature [3][4][5][6][7][8][9][10][11][12][13][14]. The black discoloration usually develops after taking minocycline, a tetracycline derivative, for several years. Thyroid tumors associated with black thyroid are extremely rare, but may include adenomatous hyperplasias, adenomas, and papillary and follicular cancers [3][4][5][6][7][8][9][10][11][12][13][14]. To our knowledge, however, hyalinizing trabecular tumor (HTT) arising in black thyroid has not previously been reported.
CaseA 47-year-old woman presented with a 5-year history of a solitary thyroid nodule. She had a history of taking minocycline intermittently over 9 years for aphthous stomatitis and oral ulcer of Behcet's disease. On examination, a mild black discoloration of the teeth and gums was identified (Fig. 1), in addition to the palpable nodule. Neck ultrasound disclosed a wellcircumscribed hypoechoic nodule, measuring 2.0-cm diameter, in the left thyroid. Fine needle aspiration biopsy (FNAB) revealed a few clusters of follicular cells with nuclear clearing, grooves, and pseudoinclusions; and a BRAF mutation (V600E) was detected by the dual-priming oligonucleotide (DPO) primer method. These findings were suspicious for papillary thyroid carcinoma. A near-total thyroidectomy with central compartment node dissection was performed, and intraoperative frozen section of the nodule suggested the